1. Field of the Invention
The present invention relates to an ornamental device which may be used in an aquarium to circulate particulate material in a cascading manner and more particularly to an ornamental aquarium fountain which is adapted to circulate a fixed quantity of sand in a cascading or waterfall like manner.
2. Description of the Prior Art
An aquarium sand fountain is primarily a decorative accessory which may be used to enhance the aesthetic appearance of an aquarium. As such, sand fountains may be designed to have any number of decorative or thematic facades which may add to the overall appearance of the aquarium.
Although primarily decorative, a sand fountain may serve the collateral purpose of helping to aerate the supply of water contained in the aquarium tank. As might be expected, the water in an aquarium tank must be regularly aerated in order to provide the occupying fish a fresh and ample supply of oxygen.
FIG. 1 illustrates a cross section of a typical example of a sand fountain 10 having been completely immersed in an aquarium tank. The prior art sand fountain 10 is generally constructed of a substantially hollow housing 10 having a lower chamber 14 and an upper chamber 16. The chambers are separated by a partitioning wall 18. As indicated in FIG. 1, the upper chamber is completely filled with water. Extending outwardly from the base of the housing is a receptacle or collector which is used to contain the fixed quantity of sand which is to be circulated in a cascading manner through the sand fountain 10. The housing 10 further includes a flexible air lift tube 26 which extends between the upper and lower chambers 14, 16. The air lift tube functions as the conduit through which the fixed quantity of sand is circulated.
As can be further seen in FIG. 1, the inlet end 28 of the air lift tube 26 partially extends through the housing wall and is in contact with the sand held in the collector 22. The opposite or outlet end 32 of the air lift tube 26 extends through an opening 34 provided in the partitioning wall 18 and is located adjacent a sand discharge opening 38 which is directly over the collector 22. In this manner as the sand is lifted upwardly through the air lift tube 26 and expelled through the outlet end 32, the sand which exits through the discharge opening 38 will again be collected for recirculation through the sand fountain.
In order to initiate the upward flow of sand held in the collector 22, a supply of air must be forced into the tube 26 at a point between the inlet end 28 and outlet end 32. In the typical example, the air lift tube 26 is provided with a nozzle 40 which extends from the section of the air lift tube 26 adjacent the inlet end 28. The air supply is introduced through a hose 42 which is attached to the nozzle 40 and which extends through an opening 44 in the back wall of the housing. Although not shown in the drawing, the air hose 42 continues through the tank water, over the neck of the tank and connects to an air pump which is typically energized through and electrical line.
In operation as air is pumped into the air hose 42 and into the air lift tube 26, a vacuum is created by the rising air which draws sand and water from the collector 22 up through the inlet end 28 of the air lift tube 26 and out through the outlet end 32. As the sand exits the air lift tube 26, it is expelled into the upper chamber where gravity causes the majority of the rising sand to gently cascade downwardly toward the collector 22 where the sand is recollected for further circulation through the fountain.
A portion of the sand, however, may remain trapped in air bubbles which result from the introduction of forced air. In order to permit the forced air and rising air bubbles to escape the chamber, an air escape opening 50 is provided at the center of the top wall 52 of the sand fountain 10.
In the past, a quantity of sand has been lost due to the sand trapped in the rising bubbles. In order to prevent the trapped sand from exiting through the air escape opening 50, the typical device teaches the use of a fine mesh screen 54 which acts as a barrier between the interior of the fountain and the remainder of the tank. As a rising air bubble strikes the mesh screen 54, the bubble is burst thereby releasing the trapped sand and allowing the sand to fall back toward the collector 22 along the partitioning wall 18.
Although this is a generally effective method of preventing sand from escaping through the air escape opening 50, over time sand may become trapped within the fine openings of the mesh screen 54. As the sand accumulates within the openings of the mesh screen 54, the flow of the escaping air bubbles is restricted. Eventually, the bubbles are forced from upper chamber 16 through opening 38. This is esthetically undesirable and leads to sand falling outside the range of the collector 22. Over time this results in the loss of a considerable quantity of sand.
A further problem which has been noted with the typical device is the use of the flexible air lift tube 26. Over time the air lift tube may kink and narrow the diameter of the air lift tube 26 thereby restricting the free flow of water and sand through the air lift tube 26.
A still further problem which has been encountered with the typical design relates to the placement of the outlet end 32 of the air lift tube in relation to the air escape opening 50 in the upper chamber of the housing. In particular, the placement of the air escape opening 50 in the top wall of the housing results in all the atmospheric air being forced out of the upper chamber by the rising water level as the sand fountain is immersed in the aquarium tank. In the fully immersed sand fountain the water level within the upper housing is thus at the maximum level adjacent the top wall.
Another problem associated with prior sand fountains is the clogging of air nozzle 40 and air hose 42 with sand when the air pump is turned off. Sand traveling through lift tube 26 settles downwardly by gravity and enters nozzle 40 when the air pump is deactivated. This can lead to clogging of the air nozzle.
A need therefore exists for a sand fountain which optimally transfers sand from the collector through the sand fountain housing and back to the collector without a significant loss of sand.
A further need exists for a sand fountain which permits the free escape of the introduced air without having trapped sand escape with the air.
A still further need exists for a sand fountain which allows for the free unrestricted passage of sand and air through the fountain housing.
Yet a further need exists for a sand fountain which provides for a pocket of air between the air lift tube and the air escape vent.
A need also exists for a sand fountain which prevents clogging of the air inlet nozzle with sand when the air pump is deactivated.